I've a 6d.
Yes, the canon wifi app is pretty limited.
However, DSLR controller from the android store pretends to be a normal computer running EOS Utility to the camera. As such, it can do it all!
Bracket, HDR, transfer raws, tethered shooting, etc, etc.
In practice, i found it a bit patchy while doing tethered shooting through wifi. It drops out sometimes and the follow-shoot (take a pic and the phone displays the last pic) doesn't save to phone at the same time.
According to the dslr controller dev it's got something to do with the 6d having a "simplified" WFT-like implementation that doesn't work the exact same way as the WFT for his 5d3 he used.
But, I could 6d-wifi to laptop and then RDP from phone to laptop and achieve same functionality.